1. Field
The disclosures herein relate to combustion engines, and methods and devices for measuring their physical operating parameters. More specifically, the disclosures relate to non-intrusive methods and devices for measuring the operating parameters of a piston driven combustion engine while it is running.
2. General Background and State of the Art
Combustion engines are driven by pistons that move as the result of explosions within sealed chambers, or cylinders. Typically, combustion engines utilize a plurality of cylinders to generate sufficient energy. Each cycle of the engine is defined by a sequence of cylinder firings. Because it is desirable for an engine to produce a stable level of energy throughout each cycle, it is necessary that the cylinders of a combustion engine fire at substantially regular intervals. It is also necessary that they all produce substantially similar levels of energy. Should one cylinder be off balance, such as by firing at the wrong time or by producing too much or too little energy, the engine may not operate efficiently or smoothly.
Therefore, it is helpful to have methods for diagnosing cylinder balance problems within an engine. However, due to the mechanical complexity of piston driven combustion engines, accessing individual cylinders for inspection and analysis may be tedious. Moreover, the very nature of a piston's operation and the variety of moving parts associated with an engine can cause close inspection of the cylinders to be a dangerous undertaking. Therefore, certain methods for detecting cylinder balance problems have been developed, in which direct access to the engine's cylinders is not required. For example, some known methods involve monitoring the electrical output of an alternator for deviations that might be caused by an cylinder imbalance. However, such methods are still fairly tedious in that they involve direct access to the alternator, which may not always be easily accessible. These methods also involve direct electrical connections to the alternator, which could both be tedious and run the risk of introducing an electric short or other malfunction to other equipment or systems that are housed in proximity to the engine.